The present invention relates to impellers for centrifugal compressors and is concerned in particular with the shape of the vanes or blades of such impellers.
Typical compressor impellers currently in use comprise a hub portion adapted to be mounted on a rotatable drive shaft and integrally connected to a coaxial disc portion which lies in a plane perpendicular to the axis of rotation of the hub. A series of vanes or blades are mounted on the front face of the disc and hub portions for imparting to air or other gases supplied to the impeller the required motion generally radially outwardly relative to the disc portion. For this purpose, the vanes or blades themselves extend generally outwardly from the hub portion although many variations are possible. For example, the vanes or blades may be truly radial or they may be backswept relative to a radial direction. Such backswept blades can be curved or straight. Frequently, the vanes or blades consist of main blades interspaced with so-called splitter blades which are of shorter axial length than the main blades.
It is an object of the present invention to provide a modified form of blade or vane shape which results in increased isentropic efficiency for the impeller.